Improvements in childhood cancer treatments have lead to a survival rate of more than 80%, but 2/3 of the survivors further develop at least one severe complication, notably metabolic disorders. Radiation therapy seems to be the most prominent risk factor. Complications only arise in adulthood, many years after treatment, suggesting memorization of ionizing radiation potentially involving epigenetic modifications. In this project we aim to characterise the effect of ionizing radiation on the epigenome of skeletal muscle and white blood cells in childhood cancer survivors, to address the mechanisms responsible for the metabolic defects and to identify early markers of metabolic complications.